为什么mongo-java-driver不存在eq？

Question

我在mongodb Java教程中找到了有关如何从mongo集合中查询的信息，但是eq它们对我来说不起作用！您知道如何使用mongo和java过滤集合中的文档吗？

这是我的尝试：

package Database;

import org.bson.Document;

import com.mongodb.MongoClient;
import com.mongodb.MongoClientURI;
import com.mongodb.client.FindIterable;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;

public class StackOverflow {

    public static void main(String[] args) {

        // insert something to mongo:
        final String URI = "mongodb://localhost:27017";
        final String DB = "StackOverflowQuestion";
        final String COLLECTION = "eqDoesntExcist";

        MongoClientURI connection = new MongoClientURI(URI);
        MongoClient mongo = new MongoClient(connection);
        MongoDatabase database = mongo.getDatabase(DB);
        MongoCollection<Document> collection =  database.getCollection(COLLECTION);

        Document doc = new Document("name", "Troy").append("height", 185);
        collection.insertOne(doc);

        doc = new Document("name", "Ann").append("height", 175);
        collection.insertOne(doc);

        // read something from mongo
        FindIterable<Document> findIt = collection.find(eq("name", "Troy"));
        // ERROR!!! the method eq(String, String) is undefined!

        mongo.close();

    }

}

我想要类似的东西：

SELECT * from eqDoesntExcist WHERE name = "Troy"

Answer 1

您可以将eq Filter那里用作：

 Bson bsonFilter = Filters.eq("name", "Troy");
 FindIterable<Document> findIt = collection.find(bsonFilter);

否则使它看起来像doc建议的方法包括为方法调用静态导入 Filters.eq

import static com.mongodb.client.model.Filters.eq;

并进一步使用与您相同的代码：

FindIterable<Document> findIt = collection.find(eq("name", "Troy")); // static import is the key to such syntax